1. Field of the Invention
This invention relates to topical compositions and methods of using them for reducing pain and promoting healing of burn related wounds.
2. Description of the Related Art
Skin is the largest organ of the body, and performs a critical function as a protective waterproof covering for the entire body. Skin contains many sensory nerve endings which keep us informed regarding our external environment, as well as myriad blood vessels which aid in temperature regulation. Skin is modified for different areas of the body, and forms a thick, heavy epidermis on the palms of the hand and palms of the feet, as compared to the thin layer over the rest of the body.
Skin is composed of two layers. The outer layer, the epidermis, contains several layers of stratified epithelial cells, with increasing amounts of protein keratin in the outermost layers. This arrangement decreases excessive water loss from the skin surface and renders the body relatively insensitive to minor abrasions and injuries. Furthermore, the epidermis has a limited distribution of nerve endings and is devoid of blood vessels so that one can shave off several layers of cells without blood loss or pain.
The stratum germinativum is the innermost layer of the epidermis and contains several layers of cells undergoing mitosis. The stratum corneum is the outermost layer of the epidermis, and makes up most of the epidermis. The flattened, dehydrated cells of the stratum corneum are constantly flaking off, often in irregular patches, for instance, after sunburn, and are replaced by cells migrating towards the surface from the deeper epidermal layers. The dead cells provide an effective covering which protects the entire body against water loss and is also a poor conductor of heat. Thus, brief contact with a hot object does not burn the skin.
However, longer contact with hot objects can result in destruction of skin and in vascular damage. While the body is capable of regenerating skin and healing minor burn related wounds without medical attention, more substantial burns require first-aid or even medical attention.
Of the injuries to the skin, burns are perhaps the most painful, and so treatment of skin burns involves not only treatment to expedite healing, but also treatment to reduce or control pain. Skin injuries are difficult to treat due to the constant exposure of the skin to the dehydrating effect of the aerobic environment and to movement. A further concern with burn related wounds is the increased susceptibility to infection. Severe skin burns largely diminish the protective mechanisms of skin against infection, and leave necrotic tissue.
In the past, skin burns have been covered with dressings such as salves, vaseline, and fibrous or synthetic polymer bandages, in an effort to prevent dehydration, protect against heat loss, prevent bacterial infection, and to maintain a moist environment about the wound to facilitate debridement. Conventional bandages are made of materials such as natural or synthetic fibers. One problem with such conventional covers is that, as the skin exudes serum an pus, this exudate is absorbed by the bandage. This proteinaceous material provides a culture medium for bacteria. Further, as the exudate hardens, the bandage is likely to become adhered to the skin. As the bandage is removed, the scab is also frequently removed. This can be extremely painful.
Various compounds have been developed as an alternative to, or for use with, bandages. For example, U.S. Pat. No. 85,385 (Hughes) teaches a medicinal compound suitable for treatment of skin ailments including burns, which composition is made by mixing and simmering cider-vinegar, molasses, spirits of turpentine, salt, saltpeter, oil of vitriol, and olive oil.
U.S. Pat. No. 321,839 (Neuer) teaches a medicinal compound for treatment of skin wounds, comprising thymol, boracic acid, potassium chloride, sodium chloride, and oil of wintergreen.
U.S. Pat. No. 390,534 (Tomlinson) teaches a lotion for treatment of sores, wounds and the like, comprising water, gambier extract, salt, and sulphuric acid.
Recently improvements have been made in bandages by the provision of a thin perforated non-adhering plastic film between the bandage and the wound. However, exudate remaining between the plastic and the wound, and this provides an excellent medium for bacterial proliferation.
Even more recently a new class of bandages has been developed of natural or synthetic materials which are water swellable, i.e., they absorb water without dissolving in water.
Exemplary of these is U.S. Pat. No. 4,732,755 (Grana), which teaches the application of sodium polyacrylate powder as a dressing over the skin burn area, and wetting the powder such as by spraying with distilled water, until the powder becomes moist. The outer wetted surface of the moistened powder dries to form a parchment like surface, and may remain in place for 2-3 weeks.
U.S. Pat. No. 4,837,019 (Georgalas et al.) teaches a skin treatment composition for treating burned skin, which composition is capable of counteracting moisture loss and promote healing, and which comprises a moisturizing component formed of polyglycerylmethacrylate, glycerine, allantoin, panthenol, amino acid complex, and fibronectin.
U.S. Pat. No. 5,009,890 (DiPippo) discloses a burn treatment product in the form of a water-soluble, biodegradable gel, the active ingredients of which are water and Tea Tree Blend. A gum material is used to maintain the water and Tea Tree Blend in a gel state.
A number of compositions have been developed for the treatment of skin burns, but these compositions contain medications which are expensive and not readily available.
In each case discussed above, the composition is either expensive or is formulated from ingredients which is not readily available. Further, the application of various of the prior art compositions to a burn may require medical training and constant attention. Further, various patients may have reactions to certain of the non-naturally occurring pharmaceutical compositions.
In view of the foregoing, it is an object of the present invention to provide a topical composition for treatment of skin burns which eliminates or minimizes the above-mentioned and other problems, limitations and disadvantages typically associated with conventional topical compositions, and to provide a topical composition which is inexpensive, easily obtainable, simple to manufacture, easy to apply and use, reliable, storage-stable, and which does not necessarily require medical training to use.